EWG's Tap Water Database — 2019 UPDATE



South Huntington Water Department

1,4-Dioxane is a solvent classified by the EPA as a likely human carcinogen. It contaminates groundwater in many states due to industrial wastewater discharges, plastic manufacturing runoff and landfill runoff. Read More.

Animal studies show that 1,4-dioxane can target the liver, kidneys and respiratory system, and that prenatal exposure can harm the developing fetus. The State of California has set a Public Heatlh Goal of no more than 1 part per billion of 1,4-dioxane in drinking water. The state of Massachusetts sets a legal limit of 0.3 ppb, and New Hampshire's limit is 3 parts per billion. There is no national drinking water standard for this contaminant.

Click here to read more about 1,4-dioxane.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20130.0650 ppb41ND - 0.260 ppb
20140.0614 ppb72ND - 0.260 ppb
20150.514 ppb76ND - 1.000 ppb
20160.800 ppb11ND - 1.60 ppb
20170.650 ppb11ND - 1.30 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.35 ppb

The EWG Health Guideline of 0.35 ppb for 1,4-dioxane was defined by the Environmental Protection Agency as a one-in-a-million lifetime risk of cancer. Values greater than one-in-a-million cancer risk level can result in increased cancer cases above one in a million people.

ppb = parts per billion

All test results

Date Lab ID Result
2013-11-19781560.260 ppb
2014-04-1578121 0420140.260 ppb
2014-05-12UCMR3 EP016ND
2014-05-12UCMR3 EP013ND
2014-05-12UCMR3 EP0120.170 ppb
2014-05-1478137 05/14/2014ND
2014-05-14UCMR3 EP007ND
2014-05-16UCMR3 EP015ND
2015-01-2378132 012015ND
2015-01-2378148 0120151.000 ppb
2015-01-2678152 0120150.1000 ppb
2015-04-2378130 420150.810 ppb
2015-07-2778148 720150.940 ppb
2015-07-2778132 720150.280 ppb
2015-10-2178130 10150.470 ppb
2016-08-230.800 ppb
2017-02-220.650 ppb